Question

The ion of an element has $3$ positive charges. Mass number of the atom is $27$ and the number of neutrons is $14$. What is the number of electrons in the ion?

• A. $13$
• B. $10$
• C. $14$
• D. $16$

Answer 1

The correct option is B

$10$

Given:

Number of positive charges on ion$=3$

Mass number$=27$

Number of neutrons$=14$

Formula used:

Mass number$=$Atomic number$+$Number of neutrons

Calculate the atomic number of the element:

Mass number$=$Atomic number$+$Number of neutrons

Thus,

Atomic number$=$Mass number$-$Number of neutrons

Thus,

Atomic number$=27-14$

Atomic number$=13$

Thus, the atomic number of the element is $13$.

Calculate the number of electrons in the neutral atom:

In a neutral atom, the number of electrons is equal to the atomic number.

Thus,

Number of electrons in the atom$=13$

Calculate the number of electrons in the ion having three positive charges:

An ion having $3$ positive charges is formed. This shows that the atom has lost $3$ electrons.

Thus,

Number of electrons in ion$=13-3=10$

Thus, the number of electrons in the ion is $10$.

Thus, Option (B) is the correct option.